I am flabbergasted that as a society we aren't rushing to build a 100 metre wide telescope mirror large enough for us to directly image the spectra of the potentially habitable exoplanets around us.

A telescope this large could tell us whether any of these potentially habitable planets contain oxygen, and thus, biological processes.

Yet thanks to funding cuts in science the biggest telescope we have in the pipeline right now is one with a 30 metre mirror.
This telescope won't be big enough, and as a result, our failure to push now for bigger sizes is almost certainly going to push back for decades humanity's ability to answer one of the most important questions we face:

Very large telescopes can achieve great resolving power, but they run up against atmospheric turbulence, particularly in many of the spectral regions we care about for checking out exoplanets. Radio light passes right through the atmosphere for the most part, which is why you see very large radio telescopes, but they're not very practical for infrared or visible light scopes.

Space-based telescopes are a better avenue. You can achieve much better resolution in practice with a much smaller telescope. There's no atmosphere to block you, and instruments can capture light of any frequency. Cost is the main disadvantage, but delivery of satellites (and maintenance) to space is getting cheaper and cheaper.

All of which is to say that I agree we should be spending more on astronomy. That was your main point, of course. I disagree with the particulars, and think we should be more willing to go to space.

adaptive optics on earthbound telescopes have allowed them to easily surpass hubble's resolution nearly a decade ago. it's also a lot easier to service telescopes on the planet than something orbiting at the ideal L2 point, some 1.5 million km from earth.

This is extremely far from my area of expertise so I am probably wrong, but I imagine that at some point we will advance earth based telescopes to the point where we get diminishing returns when considering atmospheric disturbance.

At that point, it will make more and more sense to launch space based telescopes. But... if we wait until we reach that point in the diminishing returns curve, than we lost valuable innovation time/expertise in space based technology.

My hunch is that if we wanted to get the best telescope tech in any given period of time, we should do both and watch as the two types of technologies converge.

The James Webb Space Telescope, nicknamed the telescope that ate astronomy, has cost an enormous amount of money due to the need to get everything aligned absolutely perfect before launching because there will be no chance for repair.

In comparison, with adaptive optics ground based telescopes have a lot more leeway to be fixed and corrected.

(That said, if astronomical interferometry can achieve the same result as a 100Metre telescope, then let's do it that way! How is less important than making sure we have something in our pipeline within the next decade that can be capable of directly measuring the spectra of exoplanets.)

What is the practical limit for a size and weight of an object that we can realistically put into space now? I imagine that a, for example, 10meter wide lens would be extremely heavy and can not be really split into pieces for shipping. How much smaller space telescopes are for the same performance?

Fascinating video, but honestly the only thought that kept going through my head is: they've overcomplicated this.

Despite it's impressive number of steps, this does not look like good engineering.

Instead, it looks like a design by committee, with engineers going drunk on complex parts coming together rather than dumbing down the unfurling of this telescope down to its most basic possible mechanism, with the fewest moving parts possible (where failure is chronically always possible).

Seeing how overcomplicated this is, it's no surprise it cost $10 billion to build.

You're looking at a high-precision instrument, that's being fit inside a distinctly finite space and mass budget, that will have to operate for years (possibly decades), and which is beyond reach of any conceivable service mission for a very long time.

Movement, thermal control (the Webb operates in the low end of the visible spectrum, through the infrared, so its temperature itself is critical), alignment, and drift, all matter.

And every piece of equipment has to be tested and trialed to the maximum extent possible.

Space X's Falcon Heavy is supposed to launch in november with a 57 ton payload. I'm not sure how big the payload can be.

I wonder if you could make one with a few bits of lens that fold out? They'd have to be positioned more accurately that one wavelength of light (to ~100nm say or a 10,000th of a mm) which is tricky on earth but might be doable in space where you don't have gravity making things flop?

The world had less reliable housing, less clean water, less reliable food, worse healthcare, and more physical conflicts in the 60s, and we still had the Apollo program put people on the moon.

Only the most pathetic hacks would argue that we are the worse for having invested that money to push the bounds of exploration.

At a point, there are 6 billion people on the earth, and there will always be _some_ problems unsolved, whether that is because a few countries are trying to collapse, or because we have found new first-world problems to agonize about in the US.

It's a question of whether we will spend 10x the cost to solve the last 10% of those problems, or spend that money moving forward as a civilization.

The Apollo program did result in significant advances in science and technology.

Had we put the same resources into solving other more earthbound problems would we be better off? Maybe we could have developed a better, standard, safer nuclear power plant design and could have left coal and oil behind 30 years ago. And we would not be discussing climate change or at least not the idea that it was man-made.

There are some very good arguments for increasing space funding, and this is not one of them. It seems like you're just saying "social problems can't be fixed, so we should ignore them." It's also weird that you don't consider bringing clean water, health care, etc. to more people to be "moving forward as a civilization".

You might, for example, instead point out that even extravagant space budget proposals are a drop in the bucket compared to military spending.

> The world had less reliable housing, less clean water, less reliable food, worse healthcare, and more physical conflicts in the 60s, and we still had the Apollo program put people on the moon.

Of course, you do realize that statement could also read: "When we ran the Apollo program, the world had less reliable housing, less clean water, less reliable food, worse healthcare, and more physical conflicts."

Neither of these statements are particularly good at answering the question: How much do we gain by investing money in space exploration versus something else?

Let's assume a 100-meter telescope is 10x the cost of the proposed Thirty Meter Telescope. That means it would cost about $14 billion to build. If the U.S. and E.U. split the cost it would take about $14 for every person and child to build this. If you split the cost out to a decade, it'd be about $1.40 everyone had to pay out every year. This is a matter of priorities, not there being a lack of resources.

What is most? Is it more than 50%? Then maybe, but certainly not for 100 years. Or is it the vast majority? Because GP did say "anyone" in his post. Then I'd like to quote:

Almost every fourth person in the EU still experiences at least one of the three forms of poverty or social exclusion.
Monetary poverty is the most widespread form of poverty, affecting 17.3 % of EU residents in 2015. Severe material deprivation and very low work intensity follow, affecting 8.1 % of the EU residents and 10.6 % of EU citizens aged 0 to 59, respectively.

Anyone does not mean most, you may infer he meant something different but I prefer responding to what people actually say rather than what I think they meant as I'm not a mind reader and neither is anyone else and much disagreement comes from not listening to others words because you incorrectly think you know what they're trying to say. Tons of people (tens of millions) in the west continue to struggle with basic life needs, poverty is not remotely a solved problem in the west and he quite literally said it was.

Oh well I stayed in Pakistan cities and villages and farms and there's clean water, housing and mobile broadband... Sorry to hear the state in India - I incorrectly assumed they were ahead due to higher GDP per capita.

"ISLAMABAD: Eighty-four per cent of the population does not have access to safe drinking water in a country where commercial banks posted windfall profits exceeding Rs475 billion in three years, the Senate was told on Tuesday.

Quoting a study, Provision of Safe Drinking Water, conducted by the Pakistan Council of Research in Water Resources (PCRWR), Minister for Science and Technology Rana Tanvir Hussain said only 72pc of water supply schemes were found to be functional, and 84pc of those had supplied water that was not fit for consumption."

This article was published March this year. Maybe the report in question was alarmist, I don't know.

In case dawn.com isn't a reputable source, here's a number of other articles covering it:

"The outcome of the survey conducted in the domains of 21 districts of the Punjab province,
has revealed that water supply schemes are providing piped water supply for drinking
purposes to meet household needs and for other multiple uses to an enumerated population of
19.017 million persons on 2408 surveyed water schemes. The survey has however, summed
up that the performance of these schemes in terms of providing water in an adequate quantity
and of safe quality, is extremely poor. This inability and inefficiency may be scaled from the
fact that 35 percent of the schemes are presently not functioning. As a result, nearly 61
percent of the total enumerated population remains unserved by the water supply schemes.
More alarming situation is that 88 percent of the functional schemes are providing unsafe
drinking water to the consumers. It is also notable that, on province basis, the average water
charges per scheme figure out to Rs. 64 per month. "

"For Pakistan’s majority, the main source of drinking water is groundwater. The most common instrument for extracting groundwater in rural areas are the hand pump and the motor pump. Hand pumps and motor pumps together provide 61 percent of households with drinking water; in rural areas this percentage rises up to 70. "

Note that the point was not to criticise Pakistan - it seems like they are putting in quite an effort to modernise the systems. It's just that lot of these things look better on the surface and so are easy to underestimate the seriousness of the challenges.

E.g. if you have a well or running water, and no alternative, you use it, because no water is far worse than bad water. And most of the time chances are it'll be ok.

That makes it easy to conclude that it's probably safe even when there are flaws in the supply that can quickly render it unsafe or that makes it unsafe for sustained consumption.

E.g. arsenic leaking into the supply won't kill you from a drink here and there - arsenic is difficult to kill with, because too high concentrations makes you puke it up - but sustained ingestion of smaller doses may have severe and lasting health effect and may ultimately kill you.

(Arsenic is "interesting" in that a lot of arsenic contaminated water from pumped wells in developing countries is a result of inadequate testing in the rush of upgrading water sources from surface sources prone to bacterial contamination - as such, a lot of those pumped sources may in fact still represent an improvement, but in some cases also still represents a severe health risk)

Overall there's a great deal of progress in securing basic safe water supply. We're just not there yet. Even many developed countries regularly run into water supply issues.

I don't really care what the aliens taste like when I'll be bringing pigs, cows, and chickens on whatever ship I use to go visit them.

It is clear to me that the purpose of Earth-life is to spread and assimilate all matter that it may encounter, and the purpose of humanity is to build and launch Earth's reproductive spores.

If we are not alone, those other guys had better have some good antibiotics, because we're coming. Right now, it seems like we'll be moving at just a small fraction of c, but slow and steady can still win a race with only one contestant.

The important question is therefore "Once we're all dressed up and ready to go, whats our heading?"

So with respect to telescopes, would it be better to invest that in the ships, and simply launch toward any random nearby star, to be surveyed by the breeding population en route over the next few centuries, or would it be better to sacrifice a ship or two in order to send the ones we do build toward more promising stars?

How about we first at least try to understand life on Earth? We are definitely not alone, there are other conscious beings on this planet. After decades of studies we still have no idea what a humpback whale's song means. Bottlenose dolphins have at least 2 if not 3, sound generating mechanisms that could work simultaneously. The amount of information that can be encoded is enormous. Yet, we are still to learn what a single dolphin's call means. We know the function of some meercats' calls or praire dogs' calls, but despite 60 years of research we are yet to decode a function of at least one dolphin call, let alone something more complex like beluga chatter or a humpback song.

I'd rather not have astronomers working on decoding dolphin calls. You imply there's a shortage of biologists, and if we just suspend space exploration and divert those minds to marine biology, things will get better.

No,not exactly. There is a shortage of funding and also of creative approach. We cannot ask a question "are we alone" unless we know exactly what a whale sings about (if anything) or what crazy complicated dolphin or beluga chatter means. Besides, if we are ever to encounter any sort of alien life, how can we decode any signals or messages if we cannot even decode our own earthlings signals?

> We cannot ask a question "are we alone" unless we know exactly what a whale sings about (if anything) or what crazy complicated dolphin or beluga chatter means.

I don't follow. You could say the same thing about any Earth-bound phenomena. There is an endless supply of interesting things to study on our planet. There's also an endless supply of space exploration waiting for us. To pick one to the exclusion of the other seems very shortsighted, given that we don't know what we'll find in either place.

Seems like pursuing all avenues of exploration is the best way to move us forward.

Meanwhile, some of the smartest and most highly paid people are trying to figure out ways to get people to click more ads. Seems like we are sure squandering our limited time and resources as a species.

Noise is noise. If you put gain on the signal in general, you'll put gain on the noise too. That's why James Webb is in space and the 30 Meter Telescope (TMT) is in Hawaii, less atmosphere and clear air means less noise inputted. Still, the TMT is pretty darn good. So yes, you are correct, bigger telescope means more noise (in gestalt) while in atmosphere. THe reason bigger is better is because you can resolve smaller angles. The Fourier treatment of optics is useful here. The radius of your lenses/reflectors sets the limit of the higher spatial frequency. Low spatial frequencies pass through small lenses/refectors and high spatial frequencies pass through larger ones. Therefore the bigger the telescope, the more higher order spatial frequencies you can collect. https://en.wikipedia.org/wiki/Fourier_optics

Why not a 100 Meter Telescope? Cost and engineering. With these retro reflectors getting so big, you have to worry a lot about thermal expansion and differential levels of it across the whole surface. Also, the structure to hold it has to be monitored really closely in real time to make sure the calculations are accurate. It's not easy. Also, with modern adaptive optics, you'll have apply all the little piezo-motors across the entire surface which goes as the square of the radius, so costs go up geometrically (plus about 15% more for each doubling in surface area due to cabling, power issues, larger facilities with thicker steel beams, more janitors, etc.). If the TMT costs X, then the 100-MT should cost about 11X, and with the 15% doubling factor, its ~15X for only a 3X increase in radius.

Like with the Large Hadron Collider, if the extra cost means the difference between being able to crucially measure the atmospheric spectra of nearby exosolar planets and not being able to, then the extra cost is worth it.

I'll take getting definite answers to humanity's most pressing questions, over new tools for killing people, any day.

As would I! Unfortunately, it seems the Realist sect of International Relations seems to be en vouge these last few decades. That said, there is an existential threat to 'science' in general with these large and impossible to replicate engineering experiments. They kinda get subsumed into the 'Big Science' camp where the budgets mean more than anything else and then incentives get muddied. In the physics field, there is still enough animosity and ego between the researchers to keep it all in 'science' and the results don't get massaged like in bio where it's all 'Big Science' now and the results get tweaked.

Thanks! I just finished a 14 month class in Optics, so it's fresh for me. The alternative to putting something into space is much more preferable. No matter how big a ground based scope it is, you still have all of that air mucking up the data coming in and you just can't get as good of data. Space is just so much better, as you know, it is mostly empty of the matter we are trying to look at. Granted, for many EM frequencies, ground based is fine. But a lot of atoms we are trying to look at happen to be present in the air too, messing up the data. Space costs a lot more, but I think there is no comparison in the long run. The dark side of the moon would be a good combo of both advantages though. You could build and also maintain and modify a very very large telescope with out any air or other ground based interference. The flip side is that it would be even more remote than current space based telescopes and therefore more expensive to get things to, like people, air, water, food, and fuel. But, hey, it's the flipping Moon! Like, we have a semi-good reason to go back now! For science!

The corresponding space telescope for exoplanet detection and spectral characterization is being planned for sooner than you may expect: https://www.jpl.nasa.gov/habex/.

This, or a similar concept, is hoped to be in the upcoming National Research Council decadal survey which recommends astronomical priorities for the 2020s. Current designs require as little as 4 meters.

Stability is one advantage of space telescopes. Integration times for spectral characterization can run into days.

We know what technology we need to build. Why must we wait a full two more years for a report to get finished before even beginning funding proposals on which path to pursue, before beginning any construction or engineering?!

None of us are getting any younger. I know this is complicated technology to build, but contrast how fast technology moves in the valley compared to this, and you can see the ways in which NASA could really use a bit of startup hustle... (like back in the 60's, when NASA engineered and landed people to the moon within a decade.) There just appears to be no sense of urgency at all.

I don't have time to reply to this with the level of detail required, but I'll just say that you underestimate the level of tech needed to deploy a mirror this good, and you overestimate how much we understand the instrument design issues. That is, we don't know what to build.

The trade studies are highly complex (how big the aperture is, how long the mission is, how much propellant is needed to slew the spacecraft, what the yield will be in terms of number of spectral characterizations, whether you need an external star shade). The star shade, if needed, would be a separate spacecraft.

General comparisons to "how fast technology moves in the valley" are not specific enough to benchmark what's needed for this rather unique mission.

Anything further than a 100th of a light year past the edge of the solar system we aren't going to be able to send a probe to so why bother except to provide subject matter for sci-fi. Even if we see that there is intelligent life on that planet there's nothing we can really do about it.

If they are a few hundred years ahead of us technologically they know about us and don't care. If they are a few hundred years behind they won't be able to receive our transmissions. I know science nerds need a wondergasm, but until we get some decent deep space propulsion technology it doesn't freaking matter. Seriously, except for some cool TV shows what tangible benefit had deep space cosmology brought us in the last 40 years?

Unless they can explain to their shareholders what the benefit of that overwhelmingly long-term investment will be I don't see it happening. Maybe after SpaceX becomes a massively profitable company in the same vein as the tech giants, but not before.

Bill Gates also made it painfully clear that he wants his money to go to issues we can resolve right now here on Earth like renewable energy, clean water, fighting disease, etc, which is why philanthropists like him avoid funding anything space-related. They want to witness the fruits of their investments within their lifetimes.

Easy: Marketing the brand name. Imagine a rocket with Google painted on the side on the evening news. Updates on the construction and progress, all mentioning Google. Google setting up a Google Center that collects all the data coming down. Every discovery has Google's name attached to it. Etc.

That first of all depends what you mean by "diversity hiring". You assume it is not about meritocracy, but most diversity programs are exactly about trying to cut through biases and ensure a meritocracy. I see setting the two up against each other as largely a strawman - I don't know anyone pushing diversity programs that don't believe it is about evening the playing field rather than providing anyone with an advantage above and beyond their merits (I'm sure they do exist, but I haven't met any).

Consider this: Let's assume group A and group B both follows a bell curve in terms of abilities. Let's assume they're not equal. Maybe group B is shifted so that only 3% of group B can compete with the top 10% of group A, for example.

Now, if you hire exclusively from group A, and you due to competition for resources end up hiring from the top 20% of group A, you are losing out - there are then substantial numbers of candidates in group B that outperform people you are willing to hire from group A.

That is a non-emotional explanation for why diversity is good unless we're in a world where current distribution already accurately reflects merits:

Even if you assume that there are substantial differences in abilities between genders or races, unless you can consistently rule out that anyone in these groups are able to compete on abilities, creating an environment that is non-inclusive will leave your competitors with access to better people than you have.

The best way of ruling that out, if you believe these groups have different distributions of abilities, is to carefully control for biases and recruit on ability.

Now, if you mean quotas where metrics of abilities are ignored in favour of hiring people belonging to specific groups, then that changes the issue, though sometimes such quotas can also be justified if you have reason to believe the metrics used are flawed.

E.g. in the UK private schools tend to outperform state schools on A-level grades (equivalent, roughly to SATs / high school diplomas; used for university applications), but the conditions a top student in state school works under also makes it likely that their grades under-represents their learning abilities vs. private school students under equivalent conditions - differences in class sizes and available resources does make a difference in exam performance, and if you can correct for it, it makes sense to do so. If you don't, it may make sense to use quotas to ensure you safeguard your ability to skim the best candidates from these groups.

Incidentally, taking more students from state schools would on average be likely to take more black students, for example.

My (black, female) ex is on the diversity board of a major investment bank's offices in the UK, and is struggling with exactly this: The bank in question almost exclusively hires from a set of private schools where white men dominates, and sees "diversity" as being about attracting the few black people and women from those schools, rather than hiring by ability without looking at which schools the candidates are from, which would let in far more women and black people.

This is before taking into account other factors, such as positive PR with customer groups that hold increasing importance.

In other words, there are substantial cold, hard, emotionless reasons to push for less biased hiring, and the proponents of most diversity programs believes that these will provide more diversity through meritocracy, not despite it.

I'm all in favor of science funding, especially projects that drive and give back technology capabilities to society. But I would like to see more balance and preference to solve hunger and poverty around the world.

To me that question is high on the list as well. And preferably more so.

What is the point of solving hunger and poverty when we are unable to solve climate change? Having more people and more people who can afford luxuries will only make that problem worse. I know it's a tough argument to swallow, but that doesn't make it less true.

Finding the existence of life on another planet holds MAJOR implications for many organized and unorganized religions. It would tell us whether abiogenesis and life is common, or something truly unique.

So while discovering life on another planet wouldn't answer exactly "why we are here", it would go a hell of a long way in shaping our answers to that question.

I apologize for being semantic, but I think that would answer the 'how' rather than the 'why.' I understand what you're saying though. As for the religious, well... I believe they will absolutely find a way for there not to be any major implications. New findings will be absorbed into the obfuscatory practice of apologetics.

Even a negative finding holds important implications: if we successfully survey all of the exoplanets within 100 to 1000 light years and find no life or anything even close being habitable for humans, then it would gravely inform us of the ways in which we must preserve the Earth that we have.

Putting it bluntly: I'm not flabbergasted because I don't live in a bubble. The great majority of people in this planet have more pressing things to worry about than a 100 metre telescope, things like housing, having food for tomorrow, money, not getting killed, not getting raped, not getting exploited by rich oligarchs/the government, etc etc.

Man, I too wish we had more money for large scale scientific endeavours, but I am not flabbergasted that we don't; I can see perfectly why not.

The money is there. U.S. military spending far exceeds spending on science.

By another commentators estimate, the 100 Metre Telescope would cost ~$15 billion to build. In comparison the F-35 fighter jet program cost $168 billion, and in 10 years the U.S. will spend roughly $5.5 trillion on its military.

The point is that if you can convince people to demand a budget cuts for the military, they will almost surely demand to allocate the funds to more pressing needs than space exploration. Most people would sooner want that money spend on things that could improve their lives in a tangible and immediate way than spend it on something that does not benefit them directly in any way.

The point is to grab perspective about how achievable these goals are, using money that's being wasted in such large supply right now on tools to kill people.

If we found strong evidence of life existing on another exoplanet (due to finding oxygen in the emission spectrum of an exoplanet's atmosphere), it would be a game changer. A story of the year, and influence the outcome of the rest of our century.

It would compel, very likely spending on space probes and exploration to go way back up to levels seen in the 1960's or even higher. That was a time when we had both robust spending on space exploration and social programs...

Since money is what motivates the military-industrial complex, we only need to decide that all future telescopes will be built by armaments manufacturers, because after all the aliens could be planning a preemptive strike. Then all sorts of senators, lobbyists, etc. will be trying constantly to increase telescope spending.

This title is a bit imprecise. They detected four planets with lower bound on their masses to be down to 1.7 Earth masses. Because these planets don't transit, there are no direct measurements from their radius. They can use mass-radius relations to infer the radius of these planets, but the key finding is their masses (actually lower bounds on their masses).

Can you say they _don't_ transit? They say the planets were detected by analyzing star wobbles, which doesn't necessarily mean that the planets don't transit, just that it's not how they were detected.

I guess you're right. I know there aren't any observed transits, but I also don't know what the current constraints from monitoring the star's brightness for transit is (the star is actually so bright that it becomes hard to monitor for planet transits).

However, we have a good prior on the inclination of these planets, because we know the inclination of the dust disk around the star (https://www.scientificamerican.com/article/tau-ceti-s-dust-b...), and it is likely the planets are at a similar inclination. Because the disk isn't edge on, the planets also likely aren't, and won't transit.

"Wobble" is perhaps a imprecise term. What is actually measured is the doppler shift of a spectral line in the star. In other words, you are measuring the velocity of the star in the radial direction (towards and away from the Earth). By measuring how the velocity changes over time, you can get a orbital period for the planet. By measuring the magnitude of the velocity change, you can get a lower bound on the mass of the planet. It is only a lower bound as depending on the orbital inclination, some of the movement will be in the perpendicular direction (back and forth on the sky). We are unable to measure this movement precisely enough to detect (in most cases).

Seems like it would have to be. If you've worked out from the wobble what the mass and orbit are it would stand to reason you've either calculated or at least stated an assumption regarding the inclination.

Well it doesn't transit from our point of view, so yes, I think he can say that as the observer.

"In astronomy, a transit or astronomical transit is the phenomenon of at least one celestial body appearing to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point."[0]

I understand that. I guess I don't know how small we can reliably view transits. We can certainly see large planet transits. Perhaps planets of this size are too small to view at this distance/ with this star type with our current technology. Just because we haven't observed a transit doesn't mean the transit isn't happening. But again, I don't really know this specific circumstance.

Actually this star is not in the Kepler Field, and it is also too bright for Kepler. Even most ground based telescopes looking for transits probably haven't bothered looking at it, due to its brightness.

I really really want project Starshot to become a reality. I think this is our best bet for scoping out these near by star systems. At least within our lifetime.

If we could hit 50% speed of light we could do a fly-by mission in ~25 years. Then another 12 years waiting for the data. Honestly, ~37-40 years isn't bad for an interstellar mission. Remember the Voyager program
has been going on for that long! So we already have experience with long space missions.

The other project that needs to become a reality FAST is the construction of a telescope large enough to measure the spectra of exoplanets. Because once you find a habitable planet with oxygen in its atmosphere, you now have an irrefutable and pressing case to move fast with Breakthrough Starshot.

I would incredibly surprised if he hasn't already thought about similar things. I remember in an interview last year he stated that the Interplanetary Transport System SpaceX is building for whisking humans to mars and other celestial objects in the solar system will be tiny in comparison to the spaceships that humanity will build in the latter half of this century. Bear in mind, the ITS has more than 3x the lift-off thrust of the Saturn V, which is the largest rocket ever built.

Paul Allen provided a lot of the funding for SETI Institute's radio array design and construction, but operational budget has been really tough.

It's not quite enough to build the instruments. We have to fund the ongoing science, too. Philanthropy does play a role here, too, of course: endowments for academic research, but generally not as inspiring as making Very Large objects.

Ok, let's assume we find a warm, watery planet like Earth's within ~20 light years, and we figure out a way to travel >= 50% the speed of light, making it somewhat reasonable to get there. If the planet's gravity is greater than 10% different from Earth's, or its Day/Night cycle is much different from Earth's, wouldn't it still be a nightmare to live on.

Anatomically modern humans have lived on Earth for 200,000 years, and the creatures we descended from have lived on Earth for 541 million years. Stuff as dumb as the moon cycles affect us. How are we going to live somewhere that isn't exactly Earth?

We could try with a much more doable planet like Mars. We could find out if long term survival is impossible, very difficult, possible but difficult, or doable with the right technologies. It's shocking how little appetite there is for redirecting 50% of the budget which is currently allocated to the military to space exploration.

I understand that the military is partly a large welfare program which doesn't compete with private enterprise due to different technologies and classified material, but I wish there was a movement to invest more of that time, money, and energy on basic research, climate change, energy technologies and space exploration. It's a hard sell though because I suspect that these technologies would compete heavily with established businesses.

The military application of rockets is only reason we got the tech to reach space and military application of satellites is why we figured out how to stay there and the militaristic penis measuring between nations is only reason we reached moon.

In addition to the clarification of intentions, military spending is in fact 54% of federal discretionary spending.

Entitlement programs like SS and Medicare/Medicaid are raised on a separate tax (you can see it on your paystub), and have zero discretion in how they're spent. It's determined by statute and is automatic, not part of the budget process, and the money never really mixes with the rest of the federal budget.

If you take those out, and take out interest payments which we also don't have much choice in, military spending is 54% of the money that's actually at issue when Congress makes budget decisions.

And the answer is if you accomplished a miracle and cut military spending in half and freed up 8% of the federal budget, there would be a rioting mob charging towards the money... no... that doesn't really capture how much we're talking here... there would be a rioting mob charging the suddenly-available huge pile of MONEY MONEY MONEY MONEY MONEY and there's very little reason to believe space exploration would be any of the winners.

Having near certain evidence of life existing on another planet, due to seeing oxygen present in the emission spectra of an atmosphere of another planet, would be a true game changer for space probe and exploration funding.

Astronomy funding stagnates when its about rocks and geology. Bring real evidence of aliens into the mix and you've defined humanities focus for the next century.

If we discovered actual humans on a near-exact clone of earth, we'd still be about 50,000 years from something relevant here on Earth. Outer space is staggeringly expansive. Staggeringly. Like "your space probe is sad joke" expansive.

We could develop our own alien life right on Earth within that timeframe.

I'm not the one who downvoted your message because you can't downvote replies to your own post, but I suspect you got downvoted because you crossed threads. If you follow the "parent" up from my post, you'll see that it didn't involve the discussion about finding oxygen.

I agree with the text of your message; it just isn't an appropriate reply to what I said. In fact if such a thing was discovered I'd say all bets are off in terms of the response.

On the other hand, government funded resource for DARPA created the place we're speaking on now. You could say that created and entire multidimensional marketplace for business. I'm not sure it would have existed if it were purely down to commercials (take Gopher as an example)

> Stuff as dumb as the moon cycles affect us. How are we going to live somewhere that isn't exactly Earth?

People will get more sick, they will need more attention. But that doesn't mean that it is not possible.

Umeå is a Swedish city with a population of over 120,000. January has 33 hours of sun, while June has 286. That's fairly different from your usual place to live. But the city is a completely normal city. You need to go to more extreme situations to get a city that needs extreme changes.

So yes, there are challenges. People living in zero gravity has a lot of health problems, for example. But the most similar the planet the fewer problems there are. And it is cheaper and easier to move there.

Even at 50% the speed of light, adding in a fudge factor for acceleration/deceleration, you're still talking about a trip time of 50 yrs. Even if you go all Neon Genesis and send 15 year olds on the journey, they'll be at retirement age by the time they arrive.

In other words, you'd almost definitely have to send a generation ship. Which means you'd have to have already figured things like artificial gravity, giving birth and raising children in space, etc. It wouldn't be too hard to imagine taking earth values for day/night and gravity, and then gradually over 50 years adjusting them so that, by the time you arrive, you'd have acclimatized to those values on the new world.

Interestingly, while on earth 50 years will have elapsed, because of time dilation on the ship only about 40 years will have elapsed. It will get exponentially closer to 0 elapsed time as the speed approaches c. At 90% c only about 20 years will have elapsed [1]. Equivalently, as the travelers approach c, the distance to the destination will appear shorter.

The math is actually quite simple to do yourself, your dilation factor is just 1 / sqrt(1-x^2), where x is a percentage of c from 0 to 1. So at 0c, your factor is 1 (obviously), at .5c it's 1.15, and at .9c it's 2.294.

Divide the elapsed time in the stationary reference frame by the dilation factor and you get values that roughly agree with yours.

I'm going to show my nerd colors here but having a thought like this has almost ruined Star Trek for me. For me I often think about atmospheric pressure. There's no way that beings from so many different planets could exist on a single star ship set at 1 Earth atmosphere.

Maybe someone knowledgeable in this space can tell me, but is a planet's atmospheric pressure reliably proportional to its mass?

Yeah this is a lot of suspension of disbelief, but Star Trek has a bunch of those, so it's not so out of left field.

One common solution in SF novels is for aliens to be in an atmosphere suit, typically very high tech (thin and floating). In extreme cases, the suit would encase the whole body in gel fluid and also inject it into lungs and other orifices to withstand pressures from different gravities or ship acceleration.

In essence, you need a lot of tech to allow diverse aliens to spatially co-exist.

Edit: All of this ignores food. Typically, stories solve that with some kind of nano-replicator that can make any combination of chemicals safe for aliens to eat.

Humans manage to live in the Sahara, the Himalayas, tolerate being a hundred pounds overweight fairly well, Alaskans deal with weird day/night cycles, etc. I don't think we're quite as sensitive as you make us out to be.

Also, consider the context within which we are considering such a trip: survival of the species long term. Maybe adjusting to the gravitation and day/night cycle of a new planet is absolutely terrible. Choosing that over extinction is still the easiest choice in the universe.

I don't know about the day/night thing, but we could definitely get used to more gravity. When coming in for landing you could decelerate over the course of the last year or so at a slowly increasing rate to an effect of slightly more gravity than the planet you're landing on. You slowly grow accustomed to that and then when you land, you actually feel lighter on the surface of the planet.

"Anatomically modern humans have lived on Earth for 200,000 years, and the creatures we descended from have lived on Earth for 541 million years. Stuff as dumb as the moon cycles affect us. How are we going to live somewhere that isn't exactly Earth?"

To further your (good) point about gravitational and diurnal differences, it is worth also considering the experience of native americans in the face of novel (to them) micro-organisms brought in by europeans.

These diseases were not from another solar system and they were related to animals that had local analogs ... and yet they were devastating (up to 90% mortality in some places) to the native population.

On another planet the bacteria, viruses and fungi (not to mention the potential discovery of previously unknown biological primitives) would be completely novel to us.

I wouldn't be shocked if there was 100% mortality outside of containment/quarantine after a week or two.

EDIT: On the other hand, imagine if we found that our genetic code did contain information related to what we found offworld ... wouldn't that be fascinating ...

It depends wouldn't it? If the biology and chemistry of those organisms prove to be completely different (e.g, by not being carbon based), then couldn't their bacteria prove to be utterly inert in relation to our bodies?

I'm left wondering these same kind of issues every time there's a Mars habitation post. Having a third the gravity, microscopic dust, and a complete lack of nature (or Internet) seems to be trivial to some people.

As they say of NYC, "if you can make it here, you can make it anywhere".

People living in large urban centers are essentially 100% disconnected from any sort of natural day/night light cycles, but they still manage (with, admittedly, some negative health effects). Same deal with gravity; the human body can support people who way 2x the average for their demographic, so I don't think 10% different gravity will matter much.

In the worst case, we could probably do genetic modification or just use exogenous hormones to help adapt to weird sleep cycles.

Why would gravity be the problem? There are people that weigh twice the weight of other people same height. I guess very low gravity could affect calcium in the bones and there could be other various effects. But people are life and life is adaptable. Day/night cycle? It varies greatly on earth too. Also one person's nightmare is just life for some other.

Adaptation isn't a great issue imho, the main issue is whether the 20th century sci-fi trope of colonizing space is a good idea in the first place and I'm pretty skeptical it is. These threads always strike me as incredibly naive in just assuming we would want to go anywhere/everywhere.

Well, we'd need to apply 40 km/s of delta-v. The moon weighs 1/80th as much as the Earth. By the rocket equation, we'd have to throw the material of the Moon away from Earth at 3219 km/s or 1/100 of the speed of light in order to accelerate Earth enough.

At this point, we might have to see that it is necessary to genetically modify humans so that they can survive in these alien environments. Maybe we cannot be comfortable with 10% higher gravity, but we can _make_ ourselves be comfortable.

"The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets."

Unlike more common smaller stars, such as the red dwarf stars Proxima Centauri and Trappist-1, they are not so faint that planets would be tidally locked, showing the same side to the star at all times.

In such planets, the most habitable zone is around an equator like region where the light and dark regions kind of merge to produce a reddish sunset like hue all through the day. I think one of the planets that Kepler discovered is like that. Life would evolve to absorb these light wavelengths. So for instance plants would all look black. Nova has a great episode on these exoplanets. https://www.youtube.com/watch?v=5HZsFMqqGJo&t=793s

If we wanted it badly enough, we could get to tau Ceti with current technology. The Orion designs are sound, and could carry a population capable of sustaining itself for the 100-odd years it would take to get there.

Project Orion is awesome and I am a big supporter. Unfortunately people won't stand for the thousand some odd nuclear bombs it would take to get the interplanetary version out of the atmosphere.

Because it is so massive, building it in space also poses a problem unless we capture a iron meteorite and bring it back or mine/build it on the moon. Both of which we should really do because it would be by far the fastest ship we can build right now.

A nuclear explosion in space wouldn't push against the air and would expand spherically unless somehow contained.

Because it doesn't use conventional chemistry the presence or absence of chemicals, like ambient oxygen wouldn't change the output (like it might for a fuel air bomb) but their their properties might change it. Air will provide some resistance and fluoresce at high enough temperatures. I am curious how big this effect would be though. Debris leaving a nuclear explosion in space would only stop when it hit something and that I think is the biggest flaw with the Orion motor.

If the motor and fuel can be designed so only particles are emitted and somehow ensure that no bullet size fragments are ejected then it seems likely it could be made safe in a practical sense.

I think a slim profile and large ablative shield are two good ideas. that largely solve both of these issues.

Build something like the TransAmerica Pyramid (without the two white flanges) and put the motor(s) where the foundation would be as to make the building fly like a rocket. Put the motors on at one G and you get artificial gravity, a slim profile and damage equally distributed along the bulk of the ship and most collision will happen at extreme glancing angles.

Stop off near a comet and melt large boulders of ice to the hull. If the outer hull is tiered whipple shields there will be plenty strong and will serve as mount points for the ice. Run simple heating element through it and simplify the installation of ice as ablative armor.

Have all of the storage on the ship be on walls, cabinets, netting, shelves, etc... and bolt all the furniture down. Because when you aren't accelerating you will have no gravity.

When you want to stop, turn the ship around (using reaction wheels or attitude jets) and blow your engines at the target at 1 G to slow down for the same amount of time you burned them to accelerate. This will create artificial gravity again in the same direction you were experiencing it before because you changed the direction of thrust the same amount you changed the orientation of the ship.

You have a nuclear explosion clearing crap from in front of your ship as you slow down, not as safe as the ice, but presumably your engine(s) is tough enough to withstand a nuclear blast.

Isn't turning the ship at those speeds nearly impossible? You'd either have to slow the entire ship down first (the whole idea) or burn a ton of fuel to turn it while accelerating at a percentage of light speed, while avoiding debis and the spaceships engines explosions. I believe this is why scientists researching this prefer magnetic sails as a means to slow down. Or maybe an alternative engine scheme that doesn't require doing a 360 turn.

The reason an arrow, airplane or a rocket in atmosphere stays in one orientation during flight is unequal drag.

The feathers/fletching on an arrow produce more drag and the the arrowhead is dense and moves the center of mass really far forward. As air passes over it the center of mass is pushed back least and the part with more drag are pulled back more.

In space there is no air so rotating the ship is trivial. Consider comets or planets that are constantly revolving. Also, don't confuse turning with changing velocity and direction or travel.

In my previous example the ship would stay in constant motion even though it is turning a 180 degrees. The actual turn could be done with rockets or reaction wheels and by spending very little force to do it.

If you have ever seen Ron D. Moore's Virtuality. They based the Phaeton off of Orion and it is pretty cool to see how it would work. They have a whole sequence of dropping the nukes behind the ship and the explosions pushing the massive pusher plate.

Well, some fallout. Orion is designed to to use small, single stage atomic bombs even if it does use lots of them to get out of the atmosphere. Those individually produce much, much less fallout than the huge fission-fusion-fission bombs that are mounted on ICBMs. Getting Orion to space would produce less fallout than the Bikini Atoll test. But then again there was a reason the various nuclear powers agreed to stop testing atomic weapons in the open air.

I don't see us doubling-up on the initial missions unless it becomes really trivial to catch up. Even if technology gets a 4000 year trip down to 500, even or 100, we'd probably just let the poor 4000 year schmucks go on their way.

If it got down under a year maybe, but predicting what might happen if we invent FTL is a job for people who are deliberately making things up.

Good, the folks on the faster ship can arrive ahead of us 'poor guys' on the first ship and get stuck with all of the hard work of establishing the colony and performing any necessary terraforming before we arrive.

Believe so, but the major limiting factor is the amount of mass that you can carry to eject out the back of your ship.

The Expanse series is predicated on the development of a reactionless drive that converts energy directly into thrust without expenditure of mass. If such a technology existed, you could get going pretty fast just motoring along at a constant 1-g acceleration, and have "gravity" too.

If a planet is too small, it has a hard time retaining an atmosphere (see Mars) and a hard time sustaining the inner dynamo necessary for a magnetosphere (see Venus). For the latter, the fact that Earth is barely larger than Venus suggests that Earth might be very close to the lower bound of habitable terrestrial planet size. Bigger is better than smaller, but too big and you obviously stop being terrestrial, the atmosphere becomes too thick to breathe, the surface temperature gets too hot from pressure, and it might become impractical to escape the surface with standard rocketry due to increased gravity. I think I've read that double Earth's mass is somewhere around the suspected upper bound for reasonable human habitability.

Gravity. A rocky planet, roughly Earth-sized, will have about the same gravity as we have on Earth. Both larger and smaller planets will have a deleterious effect on human health, at least until we (our descendants) adapt (if it's even possible.)

From a practical standpoint though (assuming that every nation decided to work together) how would such a mission work?

We'd most likely need a generation ship, given that current estimates of max velocity is in the range of 0.5 to 0.8c.

That means spending trillions of dollars and putting thousands of people in a ship in orbit, sending them off and most likely never seeing them again.

But before that we'd want to send unmanned probes to:

a) test out the propulsion and other systems
b) scout the planets themselves, identify a good candidate

But the probe itself would take 20-30 years to reach + 12 more to report back.

Otherwise you're asking thousands to be explorers and guinea pigs for all this technology, with no guarantees about finding a habitable planet or coming back home. With something like the Mars mission you'd probably get volunteers without any family. People would be far more reluctant if it's a generation ship.

> Otherwise you're asking thousands to be explorers and guinea pigs for all this technology, with no guarantees about finding a habitable planet or coming back home.

That sounds like Mass Effect: Andromeda. Which is basically about that, humanity sending a sleeper ark to another galaxy (due to a perceived threat that might wipe out humanity in our galaxy), with no guarantee that there will be something there (although they did do some telescope measurements of the potential planets there).

Which has fascinating implications when considering extraterrestrial life. But at the same time it's entirely possible that the closest other life is extremely far away which would make any theoretical travel time be too long to meaningfully discover earth.

With the EMdrive it'll take around 150 years (give or take a century), so it's within the realm of possibility if we can engineer a ship with shielding that can last that long. The mission becomes an order of a magnitude more difficult if you want to put a viable human population on it... watch Pandorum for one scenario.... perhaps it's best to send a seed ship (as written about in the excellent SF story by Pamela Sargent, Earthseed)

It's a good example of the problem though. Any drive that relies on reaction mass will take too long to cross the distance to even nearby stars. The rocket equation kills the plan unless you're willing to make an absolutely ridiculous starship.

So you need a reactionless drive, which thus far is entirely science fiction.

This is even before you start thinking about micrometeorites in the way (which long transits increase the danger from), and simply maintaining complex machines in perfect working order for decades or centuries in the harsh vacuum of interstellar space with no external power source (no solar panels).

And that's before you start thinking about how we don't even know how to colonize an alien world, and unless you're willing to wait centuries to get intelligence on the planets you're flying in blind.

IMHO the answer to the Fermi Paradox is the most depressing one. Interstellar travel is too difficult and expensive. By the time it's feasible you are already well past the point of needing it. You can build endless orbital colonies and mine your home system and it's nearly unlimited resources forever. There is no need to embark on a colossally expensive boondoggle to colonize a distant solar system when everything you need is at home.

Yes, it's hard at our current tech level. But not nearly hard enough to explain the Fermi thing. I mean, take your scenario of solar system development: it'd be natural to exploit the Kuiper Belt and then the Oort, and the Oort blends into interstellar travel, as Freeman Dyson pointed out -- still quick on a geological timescale.

The problem with thinking about it on geologic timescales is that humans (and civilizations!) don't exist on geologic timescales.

It's going to be a tough sell to tell people "You need to pay an extra tax for your entire life so we can fund construction of an interstellar ship that your great grandchildren might witness the launch of, but won't arrive at its destination for a thousand years after that."

It's hard to imagine anything that could motivate the human race to do that short of the Vogon constructor fleet announcing that it will arrive within a couple of centuries, ready or not.

I meant https://en.wikipedia.org/wiki/Colonization_of_trans-Neptunia... where they're colonizing those spaces as a place to live -- supposing civilization has already spread through the solar system, we're not talking about needing some kind of super Manhattan project to spread a little farther out. You just need people who feel crowded in the already-full habitats.

Of course this is speculation, but it's one chink in the case for the cost of travel stopping life from spreading. Personally I expect fancier higher-tech faster means in the actual future, like Forward's Star Wisp scheme.